As coating material composites, chemically resistant fluororesins have been mainly used for applications requiring chemical resistances. Further, fluororesins have also been utilized in antireflective applications in displays and the like, taking advantage of lower refractive indexes inherently possessed by the fluororesins. Note that, although fluororesins have been utilized as rubbers or coating agents, it has been difficult to attain a protective coating agent which is hard and excellent in antiscratching property, due to molecular structures of the fluororesins.
Meanwhile, there have been recently developed hydrolytic silane compounds having perfluoro-alkyl groups, as well as various coating agents which are water repellent, oil repellent, antifouling, antireflective, and the like, by taking advantage of the properties of the hydrolytic silane compounds, respectively. However, since perfluoro-alkyl groups for bringing about the properties are bulky and inactive, cross-linking densities of cured coatings are lowered. As a result, although the cured coatings are made appreciably hard as compared to fluororesins, the cured coatings are still insufficient in antiscratching property.
Further, the following have been developed for the purpose of improving antiscratching properties.
Firstly, (1) there has been developed a scheme to co-hydrolyze perfluoro-alkyl group containing silanes, and various silane compounds such as tetraalkoxysilanes, as disclosed in Japanese Patent Unexamined Publication No. 2002-53805.
Further, (2) there has been developed a system to use perfluoro-alkyl group containing silane together with: a disilane compound containing perfluoroalkylene as a spacer; and tetraalkoxysilane; as disclosed in Japanese Patent Examined Publication No. H6-29332.
Moreover, (3) there has been proposed a system to use a disilane compound containing perfluoroalkylene as a spacer; together with epoxyfunctional silane; as disclosed in Japanese Patent No. 2,629,813.
By virtue of these techniques, it has been made possible to ensure the intended antifouling property, antiscratching property, close contact property, and antireflection property, at relatively satisfactory levels, respectively. However, this has resulted in decreased fluorine content rates, in a manner to rather lead to insufficient chemical resistances, which have been essentially excellent, against chemical substances such as household detergents, and particularly lead to an insufficient alkali resistance which is particularly a weak point of polysiloxanes, thereby bringing about a practical problem.
On the other hand, Japanese Patent Unexamined Publication No. 2004-315712 has disclosed a composite which contains a disilane compound having a specific structure or contains a (partially) hydrolyzed product of the compound, thereby achieving a chemical resistance at a level higher than before. However, the disclosed composite has a problem that cracks are caused therein such as upon application of high heat to the composite in the course of film-formation or other processes, or upon application of high heat to the composite after formation of a coating, and another problem that cracks are considerably caused such as upon formation of a coating on a malleable substrate such as plastics.